WO 02/15392 A2 describes such a circuit arrangement with a device for the detection of an interruption of a connecting line (OBD, Open Bond Detection). The circuit arrangement has supply terminals for the application of a supply voltage and an output for providing an output signal. In this case, the supply terminals are connected to suitable supply potentials via line connections that are to be monitored with regard to an interruption. For this purpose, a normally on MOSFET is connected between the output of said circuit arrangement and a first one of the supply terminals, said MOSFET being driven in the off state during normal disturbance-free operation. In the event of a failure of the voltage supply due to an interruption of the line connection which is connected to the second one of the two supply terminals, said MOSFET turns on and connects the output of the circuit arrangement to the potential of the first supply terminal, which can be identified as a fault state by a connected evaluation circuit. In said evaluation circuit, for the detection of said fault state, a resistor is usually connected between the output and the potential that is present at the second supply terminal during fault-free operation. Depending on the configuration, said resistor fulfils the function of a pull-up resistor or a pull-down resistor.
Circuit arrangements that demand a functionality for the identification of a line interruption are, by way of example, integrated sensor circuits which are used in motor vehicles and which have, under certain circumstances, long supply lines that must be monitored.
Such sensor circuits are usually realized using CMOS technology. In this case, the production processes are usually optimized for the production of normally off MOS transistors. Normally on transistors can be realized only with difficulty or with high outlay in respect of space, by means of such semiconductor processes.
What is more, there may be the necessity of preparing such circuits both for operation with a pull-up resistor and for operation with a pull-down resistor, with the result that a normally on transistor is to be provided both between the output terminal and the first supply terminal and between the output terminal and the second supply terminal. What is disadvantageous in this case is that when the circuit arrangement is started, directly after application of the supply voltage, a shunt current flows via these two normally on transistors between the supply potential terminals until a drive circuit provides a sufficiently large driving voltage that turns off the two normally on transistors.